The present invention relates generally to an apparatus and method for determining proper fit of a shoe, particularly to such an apparatus and method utilizing differences in temperature on the outer surface of the shoe, and specifically to such an apparatus and method utilizing infrared thermal infrared apparatus and methods.
Electromagnetic radiation is the emission of energy from a source. The visible portion of the electromagnetic spectrum includes radiation having wavelengths from about 0.38 micrometers to about 0.72 micrometers. The infrared portion of the electromagnetic spectrum includes radiation having wavelengths from about one micrometer to about 1000 micrometers.
The infrared portion of the electromagnetic spectrum is further divided into two sections, the near infrared section and the thermal infrared section. The near infrared section includes radiation having wavelengths from about one micrometer to about four micrometers. Near infrared radiation is the part of the infrared portion closest to the visible light portion of the electromagnetic spectrum. Like visible light radiation, near infrared radiation is emitted from the sun (or another source) and is reflected by an object. Near infrared instruments capture this reflected radiation, not thermal infrared radiation emitted from such object.
The thermal infrared section of the electromagnetic spectrum includes radiation having wavelengths from about four micrometers to about 1000 micrometers. The present invention relates to the thermal infrared section of the infrared portion of the electromagnetic spectrum.
Thermal infrared radiation is emitted from almost any source, whether the source is a gas, liquid or solid, providing the source is above a minus 273 degrees Celsius (absolute zero). Conventional thermographic instruments can perceive infrared radiation from sources that are about a minus 35 degrees Celsius or higher.
Thermal infrared radiation is emitted from about the first one-onethousandths of an inch of the source. Thermal infrared instruments do not see through objects James Bond style. Instead, via a thermal infrared instrument, one sees temperature or thermal patterns on the surface of the object.
A thermographic infrared instrument is similar to a conventional camera. The typical thermographic instrument includes an optical means that includes a lens that is transparent to thermal infrared radiation. The lens is opaque to visible light. The optical means mounted in the instrument directs the radiation emitted from the object, such as a shoe, to an infrared detector mounted in the instrument. The infrared detector itself may include a thermopile detector consisting of a plurality of thermocouple junctions connected in series and arranged in a radial pattern. The infrared detector conventionally includes a filter that permits the section of the infrared spectrum of interest to pass (typically, for example, from about eight micrometers to about 14 micrometers). A heat sink may be mounted on or about the infrared detector, though noncooled thermal detectors are available. The thermal infrared instrument may further include temperature sensors, such as a temperature sensor for determining ambient temperature and a temperature sensor on a “flag” that moves into and out of the incoming radiation such that the detector alternately receives radiation from the target and from the flag. The thermal infrared instrument further conventionally includes a processor for processing signals from the detector and temperature sensors to determine the temperature of the target.
An infrared thermographic camera may include a linear thermoelectric array. Such an array is fabricated using silicon microstructure processing and is composed of 120 pixels arranged in a row. By moving this linear array of detectors, a two-dimensional image is produced.
The picking and sizing of shoes is problematic and subjective. For example, a shoe customer having a size eight and one-half foot may fit into a size nine shoe in a first brand and may fit into a size eight shoe in a second brand. However, as to the first brand, the customer may also fit into a size eight and one-half shoe. Likewise, with the second brand, the customer may fit into a size eight and one-half shoe. Which of the four shoes is the best fit?
Using the sense of touch, the customer feels for her big toe. Using the sense of touch, the customer walks around the store in one size of shoe in one brand, then in another size of shoe in the same brand, then in one size of shoe in a different brand, and then in another size shoe in such different brand. She then may decide that none of the four pairs of shoes is just right and begins the process anew at the same store or at another store.
Compounding the above noted problems, shoe manufacturers may make one brand of shoe in one region or one country in one year and then may make the same brand of shoe in another region or another country in another year. As the manufacturing sites change, so does the equipment and personnel. So too do the sizes of the shoes within the same brand change, even if the “size” of the shoe is American size eight for women. In other words, within the shoe industry, there is no such thing as an “exact size” even for two otherwise identical pairs of shoes being displayed next to each other on the shelf of a shoe store at the same time because one pair may have been manufactured in Italy and the other pair may have been manufactured in the United States.
The present invention offers an apparatus and method for the customer to evaluate the fit of a shoe on the spot by permitting the customer to “see” her foot inside of the new shoe by thermal infrared imaging or by another means of imaging.